Automatically retractable extending nip sheet ejection system for a multiple output locations stacking device

ABSTRACT

In a sheet handling system with an array of multiple individual sheet stacking bins and a sheet feeding system for feeding sheets from a sheet feeding output nip thereof into selected bins, for stacking of the sheets into the selected the bins, with relative movement between the sheet feeding system and the multiple individual sheet stacking bins; an automatic nip extending system is provided for automatically moving the sheet feeding output nip out into an individual bin for improved sheet control for the feeding of sheets into the bin, and an automatic nip retracting system for automatically moving the sheet feeding output nip out of the bins for unobstructed relative movement between the sheet feeding system and the sheet stacking bins, in coordination with the relative movement between the sheet feeding system and the multiple individual sheet stacking bins. The nip extending system preferably includes a repositionable extended loop sheet feeding belt.

The present system provides improved reliability in sheet output eedingfor the stacking of sheets into selectable multiple output stackingocations, such as the feeding of various printed sheets into selectedones of he multiple bins or mailboxes of a sorter, collator, or printermailboxing unit.

In particular, there is disclosed herein a simple and low cost nipextension system for extending the sheet feeding control over sheets asthe sheets are fed into a selected bin, tray or mailbox (these terms maybe used interchangeably here) of a multi-bin stacking unit. Thedisclosed extending nip system is also, importantly, automaticallyretracted from any bins as the sheet or sheet set feeding systemproviding that extended eject nip moves between bins, or vice versa(i.e., as the bins move relative to the sheet or sheets exit positionoutput nip). (As to the latter, it is noted that moving bins systems aregenerally more suitable for sorters than for mailbox systems, for whichfixed bins and moving sheet ejection systems are generally preferable.)

In either case, the feeding control of the sheets as they are beingejected into the stacking bins, trays or mailboxes presentslong-standing known problems, for which many different solutions havebeen attempted or proposed. The numerous problems in sheet ejection intostacking bins which various sheet feeding systems have attempted toovercome or fix include problems of "hang-ups" or "fold-overs" of thesheet being ejected, curled sheets in the input to the bin, excessivesheet ejection velocity or "overshoot" in the tray or bin, skewing ofthe sheets in the stacked set in the bin by releasing the sheet in thewrong position or height, excessive "flotation" of the sheet as it isreleased and allowed to settle by gravity onto the stack, etc. Theextensive discussions of these and other sheet stacking and restackingproblems in the patent and other literature are known to those skilledin the art and need not be reiterated here.

Of particular interest here is the problem of "trail edge hang-up" infeeding sheets into stacking bins over a vertically extending stackingregistration wall, especially with the non-moving (fixed) bins of aprinter mailbox system. The trailing end of some sheets may not feed outfully into the bin, and thus come to rest "hung up" on top of thatregistration wall of the bin instead of settling down fully inside thebin. The hung-up sheet is mis-stacked, and it can also obstruct the pathof the next sheet being fed into that bin. The hung up sheet can also oralternatively be pushed up and out by that next sheet feeding inthereunder, so as to fold over in the bin and create a misfeeding or jamcondition, or change the sheet order and thus produce an uncollated setin the bin.

Another potential sheet stacking ejection problem is that an incomingsheet with a downward lead edge curl, and/or inadequate beam strength orthickness (especially thin, flimsy paper sheets) can hit or catch on thefront or upstream stacking registration wall provided in the stackingtray or bin to cause a misfeeding jam.

Typically, a stacking tray or bin has an upwardly sloping tray bottomsurface so that as the sheets are ejected therein they are slowed downby gravity and then reversed in direction to slide back down against anupstream registration wall for stacking alignment and deskewing there.However, as discussed above, that desired upstream registration wallpresents an obstruction over which all the incoming sheets must be fed.(If the stacking were downhill instead, by providing a downhill slopingtray bottom, then the stacking may be against a downstream registrationedge, but that is not typical of most sorters, collators or mailboxsystems, for various reasons known to those in the art, especially ifstapling is desired.)

For these and other reasons, it is desirable to more positively controlthe sheet feeding into the stacking tray or bin by maintaining a sheetfeeding nip control over the sheet as far out into the stacking tray aspossible prior to the release of the sheet for stacking. However,heretofore this has not been practicable in a sorter, collator ormailbox system where sheets or sets of sheets must be directed intorespective different trays, bins, or mailboxes. That is because thesheet feeding ejection system and its ejection nip must move relative tothe trays, bins, or mailboxes. That is, either the exit nip must movepast an array of stationary bins, or the bins must be sequentiallymovable past a stationary or fixed exit nip. If the exit nip wereextending out into these trays, bins or mailboxes over the upstream orinside registration wall thereof, this necessary relative movement wouldnot be possible. The extended nip would be broken off or would preventthis necessary movement of the exit nip from one bin to another.

The present system overcomes the above and other difficulties byallowing this relative movement yet also providing an extended sheetexit nip extending out into the bin. As shown in the disclosedembodiments, this can be provided automatically by an automaticextension and retraction of the extended sheet feeding nip into thestacking bin in use, with automatic retraction of the extended nip fromthe bin in coordination with the relative movement between the exit nipand the multiple bins to allow that movement to be unobstructed.

Although not limited thereto, in the disclosed embodiment there is alsodisclosed one system of automatically pivoting the extended exit nip outor in of the bins by a plural mode function of the automatic tampersystem of a moving collator unit. However, it will be appreciated thatvarious other automatic ivoting systems could be provided, such as byengagement of various cams or isengagement systems of various othertypes operative during the relative movement between the exit nip andthe bins. Likewise, the exit nip can be automatically extended into thebin by various spring or gravity pivoting or other movement systemsother than those disclosed in the embodiment herein. Furthermore, thespecific extended nip system here is merely exemplary and variousextending baffles, roller, and/or belt systems which effectively extendthe feeding nip and control over the sheet into the bin may be employed.

Prior proposed or provided solutions for improving sheet control duringsheet ejection into stacking trays in general include providingcorrugations of the sheet by exit feed rolls or belts and/or variousmovable and/or flexible baffles or guides, such as those shown in theXerox Disclosure Journal publication Vol. 6, No. 5, datedSeptember/October, 1981, page 237-238.

By way of background as to movable tampers and/or plural function tamperdrive systems and sheet feeding ejection systems for mailbox bins thereis disclosed Xerox Corporation allowed application Ser. No. 08/566,199filed Dec. 1, 1995 by the some Barry P. Mandel and others, AttorneyDocket No. D/95206, to become U.S. Pat. No. 5,639,078; and U.S. Pat. No.5,513,839 issued May 7, 1996 to Frederick A. Green entitled "Dual ModeSheet Stacking Tamper and Sheet Feeder Offset System" (D/94126). Thesepatents may be referred to in connection with the following embodimentdescription for further details of exemplary plural mode tamper systemsand exemplary mailbox systems.

Although the present system can also be applicable to various sorters(otherwise known as collators) and the like, the specific embodimentherein is a printer "mailbox" system. By way of background and furtherdetails of mailbox systems and their particular features anddifficulties, there is noted the extensive discussion thereof, and thecitation of other references thereon, in Xerox Corporation U.S. Pat. No.5,342,034 issued Aug. 30, 1994 to the same Barry P. Mandel and RichardA. VanDongen; and also U.S. Pat. No. 5,382,012 issued Jan. 17, 1995 toMandel et al. Note, e.g., that FIG. 1 of said U.S. Pat. No. 5,382,012 issimilar to FIG. 1 herein with the exception of the novel additionalembodiment features disclosed herein. Similar disclosures are in otherXerox Corporation mailbox systems patents.

Of particular interest, as to mailbox systems with retractable stackingassistance members, is the automatically pivotable set heightmeasurement finger system which is automatically inserted into andretracted from the mailbox bins of U.S. Pat. No. 5,603,492 issued Feb.18, 1997 to the same Barry P. Mandel and others.

As explained in these mailboxing systems patents, by way of background amailboxing system is normally for separating plural page collated printjobs by users or clients into respective bins for the respective users,not for the collation of a print job by separating identical individualpages into different bins. Thus, in a mailboxing system, unlike a sorteror collator, the number of sheets placed in any one mailbox bin of thearray of bins or mailboxes at any one time may vary greatly. Pluralprecollated sets of stapled or unstapled sheets may be placed inindividual bins at one time. Also, the mailbox bins are not normallyfilled sequentially. This is in contrast to a sorter or collator systemfor post-collation of the plural pages of plural sets of a print job,normally by placing one identical copy sheet of each page of the job setsequentially in each bin one at a time until one identical job set iscollated in each bin.

Another difference is that with moving bins sorters or collators, thebin spacing can be temporarily increased for the bin into which thesheets are being inserted, as is well known. However, mailbox bins arepreferably fixed, and thus cannot. Yet, mailbox bins must be relativelyclosely superposed to provide enough bins for the various users orclients. That is, for a mailbox system which is relatively compact, yetstill provides a sufficient number of mailboxes for a sufficient numberof different shared users, the sheet capacity or sheet stacking heightof each mailbox bin must be relatively limited, and the spacing betweeneach mailbox bin must be relatively limited. This provides a practicalrestriction on the amount of space available between bins for theejection of the sheets or sets of sheets into a respective bin, thusimposing further criticality on better control of the sheet ejectionpath into the bin to avoid misfeeding or jams.

A specific feature of the specific embodiment(s) disclosed herein is toprovide a sheet handling system with an array of multiple individualsheet stacking bins and a sheet feeding system for feeding sheets from asheet feeding output nip thereof selectively into selected said bins,for stacking of the sheets into the selected said bins, with relativemovement between said sheet feeding system and said multiple individualsheet stacking bins comprising an automatic nip extending system forautomatically moving said sheet feeding output nip of said sheet feedingsystem out into an individual said bin for improved sheet control forsaid feeding of sheets from said sheet feeding output nip into saidindividual bin; and an automatic nip retracting system for automaticallymoving said sheet feeding output nip of said sheet feeding system out ofsaid bins for unobstructed said relative movement between said sheetfeeding system and said multiple individual sheet stacking bins.

Further specific features disclosed herein, individually or incombination, include those wherein said automatic nip retracting systemautomatically retracts said sheet feeding output nip out of said bins incoordination with said relative movement between said sheet feedingsystem and said multiple individual sheet stacking bins to allow thatmovement to be unobstructed; and/or wherein said automatic nip extendingsystem includes a repositionable extended loop sheet feeding belt;and/or wherein said automatic nip extending system includes arepositionable extended loop sheet feeding belt mounted at its outer endto a pivotally mounted belt pulley; and/or wherein said sheet feedingsystem includes a sheet tamper system, and said automatic nip retractingsystem is operated by said sheet tamper system; and/or wherein saidautomatic nip extending system includes a repositionable extended loopsheet feeding belt mounted at its outer end to a pivotally mounted beltpulley and a movable idler roller moveable into and out of sheet feedingengagement with said extended loop sheet feeding belt at said outer endto form an extended sheet feeding nip therebetween in said engagement;and/or wherein said automatic nip extending system includes arepositionable extended loop sheet feeding belt mounted at said outerend to a pivotally mounted belt pulley and a baffle plate spring loadedinto sheet feeding engagement with said extended loop sheet feeding beltat said outer end thereof to form an extended sheet feeding niptherebetween.

In general, in various reproduction apparatus such as xerographic andother copiers and printers or multifunction machines, it has becomeincreasingly important to provide faster yet more reliable and moreautomatic and positive handling of the physical image bearing sheets,with better sheet control and reduced misfeeding, jam, and sheet damagerates. It is desirable to reliably feed and accurately register andstack sheets of a variety and/or mixture of sizes, types, weights,materials, humidity and other conditions, and susceptibility to damage.Sheets can vary considerably even if they are all of the same "standard"size, (e.g. letter size, legal size, A-4, B-4, etc.). They may have comefrom different paper batches or have variably changed size withdifferent age or humidity conditions, different imaging, fusing, etc..

The disclosed system may be operated and controlled by appropriateoperation of conventional control systems. It is well known andpreferable to program and execute printing, paper handling, and othercontrol functions and logic with software instructions for conventionalor general purpose microprocessors, as taught by numerous prior patentsand commercial products. Such programming or software may of course varydepending on the particular functions, software type, and microprocessoror other computer system utilized, but will be available to, or readilyprogrammable without undue experimentation from, functionaldescriptions, such as those provided herein, and/or prior knowledge offunctions which are conventional, together with general knowledge in thesoftware and computer arts. Alternatively, of course, the control systemor method may be implemented partially or fully in hardware, usingstandard logic circuits or single chip VLSI designs.

It is well known that the control of sheet handling systems may beaccomplished by conventionally actuating them with signals from amicroprocessor controller directly or indirectly in response to simpleprogrammed commands, and/or from selected actuation or non-actuation ofconventional switch inputs. The resultant controller signals mayconventionally actuate various conventional electrical solenoid orcam-controlled sheet deflector fingers, motors or clutches, or othercomponents, in programmed steps or sequences. Conventional sheet pathsensors or switches connected to the controller may be utilized forsensing, counting, and timing the positions of sheets in the sheetpaths, and thereby also controlling the operation of sheet feeders,etc., as is well known in the art.

In the description herein the term "sheet" or "copy" refers to a usuallyflimsy physical sheet of paper, plastic, or other suitable physicalsubstrate for images, whether precut or initially web fed. A "job" isnormally a set of related sheets, usually a collated copy set copiedfrom a set of original document sheets or electronic document pageimages, from a particular user, or otherwise related.

As to specific components of the subject apparatus, or alternativestherefor, it will be appreciated that, as is normally the case, somesuch components are known per se in other apparatus or applicationswhich may be additionally or alternatively used herein, including thosefrom art cited herein. All references cited in this specification, andtheir references, all of which are incorporated by reference hereinwhere appropriate for appropriate teachings of additional or alternativedetails, features, and/or technical background. What is well known tothose skilled in the art need not be described here.

Various of the above-mentioned and further features and advantages willbe apparent from the specific apparatus and its operation shown anddescribed in the examples below, and from the abstract and claims. Thus,the present invention will be better understood from this description ofspecific embodiments, including the drawing figures (approximately toscale) wherein:

FIG. 1 is a partially schematic frontal view of an exemplary mailboxsystem as one example of the possible application of an exemplary sheetoutput nip automatic extension and retraction system which may beprovided in accordance with the invention;

FIG. 2 is a enlarged partial view of just the exemplary retractable andextendable nip system of FIG. 1, shown in its extending nip sheetejecting position, with a sheet ejection as indicated by the dashed linewith an arrowhead thereon extending into the sheet stacking bin ormailbox;

FIG. 3 shows in the same view as FIG. 2 the position of the systemwherein the extended nip has been automatically retracted, so as not toextend into the bins, for unobstructed movement to another bin;

FIG. 4 is an alternative operating mode and system position for the samesystem shown in FIGS. 2 and 3, wherein the downstream nip forming unitis extended into the bin but the nip is automatically opened by liftingof its mating idler to allow for extending sheet edge compilingtherebetween;

FIG. 5 is an alternative, but otherwise similar, embodiment of thesystem of FIGS. 1-4 with a spring loaded sheet corrugating baffle plateforming the nip with the driven extended nip forming unit's belt andpulleys system, rather than forming the nip with an engaging idlerroller as illustrated in FIGS. 2-4; and

FIG. 6 is a partial end view of the system and operating position ofFIG. 2, i.e., facing the extended nip.

As noted above, while the embodiments of the Figures are for amailboxing system with a moving compiler/finishing system movingvertically between selected fixed mailbox bins, and while the pivotalmovement of the extending nip into its retracted position isaccomplished here by a repositioning of the side tamper system thereof,as will be further described below, this is merely exemplary of thevarious versions, alternatives and applications of the presentinvention, which will vary depending upon the particular sorter,collator, or mailboxing system and its sheet output system and therelative movement system being provided.

Referring to FIG. 1, there is shown one example of a prior artmailboxing system 10, further described in the above-cited references,as noted. In the mailbox unit 10 of FIG. 1 a vertically repositionablecompiler and finishing unit 21 is movable vertically adjacent toselected bins 11 of a vertical array of bins. Some or all of the bins 11may be locked, electronically unlockable, bins 11b, or an open top orgeneral tray 11a, a high capacity elevator stacking tray 23, or a bypasstransport 22 to another downstream unit 10. This may all be under thecontrol of a programmable controller 100 with an associated display 104and keypad entry system 102. This mailbox unit 10 is sequentially fedindividual printed sheets from an operatively connected printer 14 to aninput path 13 on to a belt transport system 26 similar to that in use inmany sorters or collators, with belt engaging rollers 25 and pivotalgates 17 providing a variable position gating system 18 for selectablygating sheets into the compiling and finishing unit 21 at differentvertical positions thereof. It will be appreciated that the unit 10could alternatively be utilized for or operated as a sorter or collatorby feeding individual sheets sequentially from sequential pivoted gate17 into and through the unit 21 directly out into a selected bin 11 onesheet per bin and moving the unit 21 after each sheet has been fed intothat bin. However, as described in the above-cited mailbox references,that is not the normal or desired function of this mailbox unit 10,which is normally to either sequentially feed all of the sheets of a jobset into one or more bins 11 designated or assigned to a particular useror group of users. If the sheets are not to be stapled or otherwisebound in the unit 21 they may be directly fed therethrough sequentiallyinto a bin to be stacked therein. In this exemplary system, if thesheets are to be compiled and stapled first, as by the stapler 16, thesheets are fed into the unit 21 and compiled and stapled therein an thenthe set is ejected into the bin, as described in the above-citedreferences. However, as also described therein, it is desirable forspace saving for the sheets being compiled for finishing in the unit 21to be able to partially extend out into the tray 11 into which they willbe subsequently ejected after stapling. This is provided by opening theexit nip, as shown for example in FIG. 4, as will be further described.

This feeding of sheets sequentially thorough the unit 21 to eject forstacking with improved control may be provided as shown in theembodiment of FIG. 2 or the embodiment of FIG. 5 by providing a closedfeeding nip 64 to be described, which nip, in the present system,desirably extends out downstream into the tray 11 during that operation,extending over the bin's upstream registration edge wall 27. Thisprovides substantially improved sheet feeding and sheet ejectioncontrol, with greatly reduced opportunities for sheet "hang-ups" orobstruction in such feeding, even for curled sheets.

Referring now to the exemplary sheet ejection extendible nip system 50of FIGS. 2-4, incorporated in this example into the mailbox system ofFIG. 1, there is provided in this exemplary system 50 two transverselyspaced apart pivotally extendible eject transport units 51, each unit 51comprising a pivotally mounted elongated belt 56, which belt 56 ismounted between an inner or upstream flanged idler roller and pulley 54and an outer or downstream pulley 58, on a pivotable arm 60. Althoughthe unit 51 could be driven directly, here it is driven indirectly, bythe engagement of flanged pulley 54 by a driven elastomeric roller 52.Roller 52 also provides, with roller 54, an upstream sheet feeding nipdrive here. That is, when roller 52 is lowered, as in FIGS. 2 and 3 butnot 4 (reference the above-cited patent descriptions), roller 52 engagesa sheet between it and idler pulley 54. The edge flanges on pulley 54can also provide some sheet corrugation feeding assistance in that nip.This plastic idler pulley 54 here is thus both mounting and driving theinside end or bight of the elongated frictional feeding belt 56. Withthe exception of the extendible arm 60 mounting the outer idler pulley58, and the portion of the belt 56 extending therearound, thesecomponents are all mounted upstream of the bins 11, so as not to haveany interference movement relative to the array of bins.

As noted, the extending outer end mounting of the feed belt 56 is anouter pulley 58 mounted on the outer end of a pivotal arm 60. The arm 60can be mounted to pivot about the same axis as the rollers 54, as here.Here, an inner end portion 60a of this pivotal arm 60 is positioned tobe engaged by, and cammed upwardly or clockwise by an extension 72 ofthe lateral sheet tamping system 70 in the compiler unit 21 when thetampers are moved out laterally beyond their normal tamping position (asmore fully described in detail in the above cited references thereon).That pivots down and outwardly the unit 51 to extend the outer idlerpulley 58 and thus the outer end of belt 56 out into the adjacent bin11.

In this system 50, the extending belt loop of belt 56 of the unit 51 ispositioned to be engaged at its outer end, at the outer pulley 58, by anidler roller 62 to form an extended nip 64. The idler roller 62 ispivotable on a mounting arm 63 into that nip forming engagement as shownby the movement arrow in FIG. 2, and is pivotable out of engagement withthe outer end of the belt 56 as shown by the movement arrows in FIGS. 3and 4. Here, this movement is independent, so that as shown in FIG. 4,for compiling sets of plural sheets in the compiler unit 21, the roller62 is pivoted up but the extended feed belt unit 51 remains downextending out into the bin, to held support the outer ends of sheetsbeing compiled, and providing a large, unobstructed, opening betweenroller 62 and belt unit 51.

It may be seen from FIG. 3 that the outer end pulley 58 which isextending the sheet feed belt loop 56 out downstream to form thedownstream eject nip position 64, automatically pivots out of the wayfor unobstructed vertical movement of the compiler/finisher carriageunit 21, as does the roller 62. Here, this is accomplished by pivotingof a "U" shaped bracket 66 which pivots counterclockwise the mountingarm 63 on which the idler 62 is mounted, as well as the arm 60 on whichthe extended feeding belt unit 51 is mounted, as shown by the differencein positions of these components between FIG. 2 and FIG. 3 and themovement arrows in FIG. 3.

The extended nip system embodiment 70 of FIG. 5 may be otherwise similarto that of FIGS. 2-4. However, there is an illustrated difference in thereplacement of the idler roller 62 and its arm 63 with a spring loadedbaffle plate 72. This baffle 72 may also have "wing" tabs 74 tocorrugate the sheet as it is fed through the downstream extended nip 76.

It will be obvious that there are numerous other mechanisms which can beused to achieve the above-described movements and functions. While theembodiments disclosed herein are generally preferred, it will beappreciated from this teaching that various alternatives, modifications,variations or improvements therein may be made by those skilled in theart, which are intended to be encompassed by the following claims:

We claim:
 1. In a sheet handling system with an array of multipleindividual sheet stacking bins and a sheet feeding system for feedingsheets from a sheet feeding output nip thereof selectively into selectedsaid bins, for stacking of the sheets into the selected said bins, withrelative movement between said sheet feeding system and said multipleindividual sheet stacking bins, the improvement comprising:an automaticnip extending system for automatically moving said sheet feeding outputnip of said sheet feeding system out into an individual said bin forimproved sheet control for said feeding of sheets from said sheetfeeding output nip into said individual bin, and an automatic nipretracting system for automatically moving said sheet feeding output nipof said sheet feeding system out of said bins for unobstructed saidrelative movement between said sheet feeding system and said multipleindividual sheet stacking bins.
 2. The sheet handling system of claim 1,wherein said automatic nip retracting system automatically retracts saidsheet feeding output nip out of said bins in coordination with saidrelative movement between said sheet feeding system and said multipleindividual sheet stacking bins to allow that movement to beunobstructed.
 3. The sheet handling system of claim 1, wherein saidautomatic nip extending system includes a repositionable extended loopsheet feeding belt.
 4. The sheet handling system of claim 1, whereinsaid automatic nip extending system includes a repositionable extendedloop sheet feeding belt mounted at its outer end to a pivotally mountedbelt pulley.
 5. The sheet handling system of claim 1, wherein said sheetfeeding system includes a sheet tamper system, and said automatic nipretracting system is operated by said sheet tamper system.
 6. The sheethandling system of claim 1, wherein said automatic nip extending systemincludes a repositionable extended loop sheet feeding belt mounted atits outer end to a pivotally mounted belt pulley and a movable idlerroller moveable into and out of sheet feeding engagement with saidextended loop sheet feeding belt at said outer end to form an extendedsheet feeding nip therebetween in said engagement.
 7. The sheet handlingsystem of claim 1, wherein said automatic nip extending system includesa repositionable extended loop sheet feeding belt mounted at said outerend to a pivotally mounted belt pulley and a baffle plate spring loadedinto sheet feeding engagement with said extended loop sheet feeding beltat said outer end thereof to form an extended sheet feeding niptherebetween.